1. Field of the Invention
The invention relates to a flexographic printing machine comprising a counter pressure cylinder, which is mounted in a printing machine frame and is intended for several printing units, which comprise printing rollers and related inking units, preferably engraved rollers with inking chamber doctor blades, and are disposed on their own brackets in such a manner that each printing roller and each inking roller on each bracket can be moved in relation to each other and both of them together can engage with the counter pressure cylinder, wherein the counter pressure roller and the printing and inking unit rollers are provided with drives.
2. Description of the Related Art
Flexographic printing machines of this type are known, for example, from the DE 29 41 521 A1, DE 34 37 216 C2, DE 37 42 129 A1 and DE 40 01 735 A1. In these prior art flexographic printing machines the brackets, bearing the inking units and the printing rollers, are connected securely to the machine frame so that in principle the possible lengths of the print are a function of the distance between the brackets or the distance between the printing rollers, measured over the circumference of the counter pressure roller. Longer printing lengths are possible only if individual printing units are put out of service.
The object of the invention is to provide a flexographic printing machine of the type described in the introductory part, with which arbitrary lengths of print can be set.
The invention solves this problem associated with a flexographic printing machine of the type described in the introductory part in that the brackets are held moveably in such a manner in guides of the printing machine frame or in guides connected to them and can be fixed in desired positions such that during displacement the axes of the printing rollers lie on the guides, which are concentric to the axis of the counter pressure cylinder.
The flexographic printing machine of the invention can be set in a simple manner to arbitrary desired sizes of print in that the brackets of the printing units that are printing are moved a corresponding distance in relation to each other or are moved by means of special drives and are fixed in positions that are set thus. The printing units that are printing can be distributed symmetrically, for example in mirror inversion to the vertical central plane of the counter pressure roller. Owing to the corresponding device and the setting of the printing units, the central counter pressure cylinder can be used for maximum printing lengths.
Printing units, which are unnecessary and inserted in guides, can be moved with their brackets into a waiting position or parking position, where they do not print.
Since the brackets or the printing rollers can be moved concentrically to the axis of the counter pressure cylinder, the drives for the printing rollers and the inking rollers can be removed centrally by the central gearwheel, connected to the counter pressure roller. However, it is expedient both for the counter pressure cylinder and for the printing and inking unit rollers to be provided with their own drives, which enable in a simple manner the maintenance of the register. Such multiple motor drives are known, for example, from the DE 34 32 572 A1.
A preferred embodiment provides that the brackets can be inserted into guides and can be removed from the same. In this manner it is possible in a simple manner to retrofit or remove the inking units or the printing units. This design makes it possible to provide, according to the choice of the operator, the printing machine with the desired number of printing units.
Even if during the printing operation there are a large number of printing units and negligible spacing between the brackets, bearing said printing units, it is possible to increase the distance between the printing units for the purpose of maintenance and cleaning.
One embodiment of the invention is explained in detail below with reference to the drawings.